Bad news for bats: White-nose syndrome approaches Wisconsin's border

A disease that has caused devastating mortality in bats is now poised to make its way into the state.

"The most recent unnerving news is that in LaSalle County, in northeast Illinois, they found white-nose syndrome in a mine," says Paul White, conservation biologist with the Wisconsin Department of Natural Resources. "That's roughly 100 miles from our border."

While measures have worked so far to prevent humans from spreading the fungus that causes white-nose syndrome, its eventual arrival in the state is considered inevitable because bats themselves migrate, as far as 280 miles. That's why it's not looking good for Wisconsin's bats. The disease has been found not only in Illinois, but also in Iowa.

When white-nose syndrome does arrive, it's predicted to decimate Wisconsin's little brown bats. "Unfortunately we're looking at a situation where the little brown bat, Wisconsin's most abundant bat, is also the bat hardest hit by white-nose syndrome," notes White.

Scientists now know that the syndrome is caused by a fungus, Geomyces destructans, which first appears as white fuzz on the bat's muzzle and wings and often leads to its death. First found in a cave in New York in 2007, the fungus spreads from one bat to another and then from cave to cave as the bats migrate to new hibernacula.

Since hundreds and even thousands of bats often share close quarters over winter, the spread of the disease and resulting mortality can be devastating. White says reports from the East Coast show populations of 20,000 bats being reduced to just 20 - a mortality rate of 90% to 100%.

The fungal spores can remain viable in a cave even without any bats present, as well as on the clothing or gear of humans, who can then transport them to new locations, says David Blehert, microbiologist with the National Wildlife Health Center.

The center, part of the U.S. Geological Survey and located here in Madison, is a national leader in the study of wildlife epidemics, from chronic wasting disease in deer to West Nile virus in birds. Besides tracking the spread of white-nose syndrome, scientists there are studying the pathology of the disease and even the bats' immune response.

The fungus requires cold temperatures to grow, so it infects bats when they hibernate over the winter months. During hibernation, bats' immune system slows way down, leaving them virtually defenseless. When the bats wake up from hibernation and their immune system kicks into gear to fight off the infection, the resulting inflammatory response itself can endanger them, says Carol Meteyer, former wildlife pathologist with the National Wildlife Health Center.

"The inflammation was so severe that as all of the immune cells started to attack the fungus, all of the tissue around it was also attacked," says Meteyer. So even if the bat does survive hibernation, it has the potential of the intense inflammation to get through.

Wisconsin has taken a lead role in stopping the spread of white-nose syndrome, passing three laws to protect bats. In 2011, the state listed the four bat species vulnerable to the fungus as threatened, and listed the fungus itself as a prohibited invasive. Also, a law requires all caves to have a prevention plan, involving strict decontamination protocols for people's clothing and gear.

So what will happen when the disease finally arrives? The loss of some major insect control. The little brown bat can eat its body weight in mosquito-sized insects each night. "If I were to try to eat my body weight in quarter-pound cheeseburgers, that would have to be roughly 600 cheeseburgers a night," says White.

So fewer bats means more mosquitoes bites and more pesticides on crop fields.

But before the bats become scarce, citizens can contribute to their conservation by helping monitor roost sites. They can even listen with an acoustic detector to bats using echolocation as they fly overhead.

"You're walking your dog, you have a piece of equipment in your hand, and normally you would just be listening to cicadas or the random car beep," says White. "Now you'll be able to basically turn up the volume on silence and actually hear the bats as they go through."

People can identify different species with the devices and even hear the bats feeding. Go to the Wisconsin Bat Monitoring Program website at wiatri.net/inventory/bats for more information.